libevent使用教程_evutil_make_socket_nonblocking_易方达蓝筹的博客-CSDN博客

一、准备

centos7下安装libevent库

yum install libevent
yum install -y libevent-devel

二、代码

server.cpp

/**
You need libevent2 to compile this piece of code
Please see: http://libevent.org/
Or you can simply run this command to install on Mac: brew install libevent
Cmd to compile this piece of code: g++ LibeventQuickStartServer.c  -o  LibeventQuickStartServer /usr/local/lib/libevent.a
**/
#include<stdio.h>  
#include<string.h>  
#include<errno.h>  
  
#include<unistd.h>  
#include<event.h>

void accept_cb(int fd, short events, void* arg);
void socket_read_cb(int fd, short events, void* arg);

int tcp_server_init(int port, int listen_num);

int main(int argc, char const *argv[])
{
    /* code */
    int listener = tcp_server_init(9999, 10);
    if (listener == -1)
    {
        perror("tcp_server_init error");
        return -1;
    }

    struct event_base* base = event_base_new();

    // 监听客户端请求链接事件
    struct event* ev_listen = event_new(base, listener, EV_READ | EV_PERSIST, accept_cb, base);
	printf("wait for client connect\n");

    event_add(ev_listen, NULL);

    event_base_dispatch(base);

    return 0;
}

void accept_cb(int fd, short events, void* arg)
{
    evutil_socket_t sockfd;

    struct sockaddr_in client;
    socklen_t len = sizeof(client);

    sockfd = ::accept(fd, (struct sockaddr*)&client, &len);
    evutil_make_socket_nonblocking(sockfd);

    printf("accept a client %d\n", sockfd);

    struct event_base* base = (event_base*)arg;

    //动态创建一个event结构体，并将其作为回调参数传递给
    struct event* ev = event_new(NULL, -1, 0, NULL, NULL);
    event_assign(ev, base, sockfd, EV_READ | EV_PERSIST, socket_read_cb, (void*)ev);

    event_add(ev, NULL);
}


void socket_read_cb(int fd, short events, void* arg)
{
    char msg[4096];
    struct event* ev = (struct event*)arg;
    int len = read(fd, msg, sizeof(msg) - 1);

    if(len <= 0)
    {
        printf("some error happen when read\n");
        event_free(ev);
        close(fd);
        return;
    }

    msg[len] = '\0';
    printf("recv the client msg : %s\n", msg);

    char reply_msg[4096] = "I have received the msg: ";
    strcat(reply_msg + strlen(reply_msg), msg);

    write(fd, reply_msg, strlen(reply_msg));
}

typedef struct sockaddr SA;  
int tcp_server_init(int port, int listen_num)  
{  
    int errno_save;  
    evutil_socket_t listener;  
  
    listener = ::socket(AF_INET, SOCK_STREAM, 0);  
    if( listener == -1 )  
        return -1;  
  
    //允许多次绑定同一个地址。要用在socket和bind之间  
    evutil_make_listen_socket_reuseable(listener);  
  
    struct sockaddr_in sin;  
    sin.sin_family = AF_INET;  
    sin.sin_addr.s_addr = 0;  
    sin.sin_port = htons(port);  
  
    if( ::bind(listener, (SA*)&sin, sizeof(sin)) < 0 )  
        goto error;  
  
    if( ::listen(listener, listen_num) < 0)  
        goto error;  
  
  
    //跨平台统一接口，将套接字设置为非阻塞状态  
    evutil_make_socket_nonblocking(listener);  
  
    return listener;  
  
    error:  
        errno_save = errno;  
        evutil_closesocket(listener);  
        errno = errno_save;  
  
        return -1;  
}  

 client.cpp

/**
You need libevent2 to compile this piece of code
Please see: http://libevent.org/
Or you can simply run this command to install on Mac: brew install libevent
Cmd to compile this piece of code: g++ LibeventQuickStartClient.c -o LibeventQuickStartClient /usr/local/lib/libevent.a
**/
#include<sys/types.h>  
#include<sys/socket.h>  
#include<netinet/in.h>  
#include<arpa/inet.h>  
#include<errno.h>  
#include<unistd.h>  
  
#include<stdio.h>  
#include<string.h>  
#include<stdlib.h>  
  
#include<event.h>  
#include<event2/util.h>  
  
  
  
  
int tcp_connect_server(const char* server_ip, int port);  
  
  
void cmd_msg_cb(int fd, short events, void* arg);  
void socket_read_cb(int fd, short events, void *arg);  
  
int main(int argc, char** argv)  
{    
  
    //两个参数依次是服务器端的IP地址、端口号  
    int sockfd = tcp_connect_server("127.0.0.1", 9999);  
    if( sockfd == -1)  
    {  
        perror("tcp_connect error ");  
        return -1;  
    }  
  
    printf("connect to server successful\n");  
  
    struct event_base* base = event_base_new();  
  
    struct event *ev_sockfd = event_new(base, sockfd,  
                                        EV_READ | EV_PERSIST,  
                                        socket_read_cb, NULL);  
    event_add(ev_sockfd, NULL);  
  
    //监听终端输入事件  
    struct event* ev_cmd = event_new(base, STDIN_FILENO,  
                                      EV_READ | EV_PERSIST, cmd_msg_cb,  
                                      (void*)&sockfd);  
  
  
    event_add(ev_cmd, NULL);  
  
    event_base_dispatch(base);  
  
    printf("finished \n");  
    return 0;  
}  
  
  
  
  
  
  
void cmd_msg_cb(int fd, short events, void* arg)  
{  
    char msg[1024];  
  
    int ret = read(fd, msg, sizeof(msg));  
    if( ret <= 0 )  
    {  
        perror("read fail ");  
        exit(1);  
    }  
  
    int sockfd = *((int*)arg);  
  
    //把终端的消息发送给服务器端  
    //为了简单起见，不考虑写一半数据的情况  
    write(sockfd, msg, ret);  
}  
  
  
void socket_read_cb(int fd, short events, void *arg)  
{  
    char msg[1024];  
  
    //为了简单起见，不考虑读一半数据的情况  
    int len = read(fd, msg, sizeof(msg)-1);  
    if( len <= 0 )  
    {  
        perror("read fail ");  
        exit(1);  
    }  
  
    msg[len] = '\0';  
  
    printf("get respond from server: %s \n", msg);  
}  
  
  
  
typedef struct sockaddr SA;  
int tcp_connect_server(const char* server_ip, int port)  
{  
    int sockfd, status, save_errno;  
    struct sockaddr_in server_addr;  
  
    memset(&server_addr, 0, sizeof(server_addr) );  
  
    server_addr.sin_family = AF_INET;  
    server_addr.sin_port = htons(port);  
    status = inet_aton(server_ip, &server_addr.sin_addr);  
  
    if( status == 0 ) //the server_ip is not valid value  
    {  
        errno = EINVAL;  
        return -1;  
    }  
  
    sockfd = ::socket(PF_INET, SOCK_STREAM, 0);  
    if( sockfd == -1 )  
        return sockfd;  
  
  
    status = ::connect(sockfd, (SA*)&server_addr, sizeof(server_addr) );  
  
    if( status == -1 )  
    {  
        save_errno = errno;  
        ::close(sockfd);  
        errno = save_errno; //the close may be error  
        return -1;  
    }  
  
    evutil_make_socket_nonblocking(sockfd);  
  
    return sockfd;  
}  

g++ client.cpp -std=c++11 -o client -levent